This invention relates to a detergent containing a combination of at least two cellulases, to a washing process using the cellulase combination and to the use of the cellulase combination for the production of detergents.
1. Field of the Invention
Enzymes, particularly proteases, lipases and cellulases, are widely used in detergents, washing aids and cleaners. Whereas proteases and lipases are used primarily for removing protein-containing or fatty soil, cellulases perform a more differentiated function in the washing process.
2. Discussion of the Related Art
By virtue of their ability to degrade cellulose, cellulases have been known for some time as softening agents for cotton fabrics, for example from DE-PS 21 48 278 and from DE-OS 31 17 250. So far as the relevant action mechanism is concerned, it is assumed that fabric-softening cellulases preferentially hydrolyze and remove microfibrous cellulose, so-called fibrils, which project from the surface of the cotton fibers and prevent them from sliding freely over one another. A secondary effect of this degradation of fibrils is intensification of the optical color impression, the so-called freshening of colors described in EP 220 016, which is obtained in the treatment of colored cotton fabrics with cellulases when the uncolored fibrils emanating from damage within the fiber are removed.
On the other hand, other known cellulases are distinguished by the fact that, as described for example in DE-OS 32 07 828, they have a cleaning effect to the extent that they are capable of removing solid inorganic soil from the fabric to be cleaned.
To obtain both these effects of cellulases desirable in the washing process, it has already been proposed on several occasions to use mixtures of cellulases, cf. for example International patent application WO 95/02675. This document is concerned with detergents containing two cellulase components, the first cellulase component having the ability to remove particulate soil and the second cellulase component having color-freshening properties. However, the choice of cellulases according to these criteria leaves important washing-related questions unanswered.
Problem soils which cannot be satisfactorily removed with conventional detergents include cellulose and paper soils. Normally, these soils are only formed during the washing process when paper, for example in the form of banknotes or paper handkerchiefs, remain in and are washed with the laundry to be cleaned, for example in pockets. The problems are attributable to the formation of large visible flocks which adhere to the washing and are not washed out.
The ability to remove soil from the fabric to be cleaned is normally referred to as single wash cycle performance. Besides ingredients with this crucially important property essential to the washing process, detergents also generally contain active substances which contribute towards multiple wash cycle performance. This is understood to be the property whereby soil detached from the fabrics can be kept dissolved or suspended in the wash liquor in such a way that it is not deposited on the cleaned fabric. This effect is also known as anti-redeposition. In the case of detergents, it is desirable that as many of their ingredients as possible, including the cellulase used, contribute towards multiple cycle wash performance through their anti-redeposition effect.